The present invention relates to the equipment for hydrolysis of peat, and more particularly to apparatus for mechanical and chemical destruction of polysaccharides of younger slightly decomposed peat.
The invention may be advantageously used in the microbiological industry for producing culture medium for cultivation of fodder yeast or as stimulator of growth of fodder yeast cultivated on culture media obtained by hydrolysis of wood or agricultural wastes.
The increasing rate of agricultural development creates an evergrowing demand for valuable vitamin-protein fodder products, such as fodder yeast to be used in animal breeding.
At present, fodder yeast is produced on the basis of hydrolysis of wood, agricultural wastes, such as maiz strimps, rice seed husk, cotton husk, straw and the like, and on the basis of processing of products of the petrochemical industry. The above-mentioned starting materials cannot satisfy the demand of the national economy in vitamin-protein fodder products, and the problem resides in finding new kinds of non-food starting materials suitable for processing into protein fodder, such as fodder yeast.
In finding a solution to this problem, the possibility of and promising results from processing a new starting material--younger slightly decomposed peat--into fodder yeast has been revealed, the new starting material being largely available and practically unused.
In view of specific physical and chemical properties of peat, it is economically inadvantageous to produce therefrom hydrolysate in the form of a solution of a mixture of sugars which constitutes a culture medium for cultivation of yeast by using conventional methods of hydrolysis in autoclaves/hydrolizers.
The attempts to make the use of younger peat economically advantageous for hydrolysis resulted in the provision of equipment in which a hydrolysate mass containing a mixture of water-soluble sugars is obtained by means of mechanical and chemical treatment of slightly decomposed peat in the presence of small quantities of concentrated sulphuric acid.
The mechanical and chemical treatment of peat is effected in an apparatus for a certain time and within a limited space in which the material being treated is subjected to mechanical action resulting in great shearing forces inside the peat particles, the attrition effect of such forces providing for breaking of chemical bonds in molecular chains, that is destruction of polysaccharides of peat occurs with the formation of homogeneous hydrolysate mass containing monosugars. Subsequent processing of hydrolysate mass containing a mixture of non-dissolved sugars results in obtaining hydrolysate, that is a solution of mixture of sugars, which is used as culture medium for cultivation of fodder yeast or as stimulator of growth of fodder yeast cultivated on culture media obtained by hydrolysis of wood or agricultural wastes.
Known in the art is an apparatus for comminution and mixing of solid substances inpregnated with liquid, such as peat.
The apparatus comprises a cylindrical casing having a vertical admission pipe and a horizontal outlet pipe tangent to the casing. A disintegrating rotor is accommodated within the casing at the outlet side thereof and consists of an inclined disc having peripheral teeth. The teeth cooperate with grooves made in the inner wall of the casing. An auger is mounted in the casing coaxially with the rotor, the end of the auger which faces the outlet is spaced apart from the disc rotor to define a working space. The rotor and auger are rotated independently on each other by means of individual drives.
The apparatus functions in the following manner.
Lump peat or other material is fed via an admission pipe or conduit into the casing where it is engaged by the auger to be displaced to meet the rapidly rotating disintegrating disc rotor.
The material is accumulated in the working space between the auger and the rotor to form a plug which is pushed through by the auger to be comminuted by the disc rotor due to the presence of teeth on the periphery of the disc and grooves of the casing, as well as due to the inclined position of the disc. The comminuted material is thrown by centrifugal force through the outlet pipe.
This apparatus cannot, however, be used for mechanical and chemical destruction of polysaccharides of peat because the construction of the apparatus cannot provide conditions required for the purpose.
The material within the working space between the auger and the disc rotor fills the entire cross-section of the cylinder to form a plug which is shorn off the end face in layers so that the material is comminuted.
In shearing any material, shear forces are developed, but such forces cannot bring about the attrition action between the particles of material because the contact of the working tool with the material occurs along a line or along a surface, rather than within a three-dimensional space.
It should be noted that the main requirement for mechanical and chemical destruction of polysaccharides of peat with considerable shearing forces is the provision of an attrition action occurring both in time and space which is necessary for breaking chemical bonds of molecular chains.
Another apparatus is known in the art for mechanical and chemical destruction of polysaccharides of younger slightly decomposed peat.
This apparatus comprises a casing accommodating an auger and a working head which are mounted axially thereof and rotated by means of individual drives. A nozzle is mounted in the casing coaxially with the head, the nozzle embracing the head and defining an annular space with the head which forms a working space for effecting mechanical and chemical destruction of polysaccharides of peat. A spring-loaded stop is mounted on the same shaft with the head, at the side of outlet of hydrolysate mass, the stop being axially displaceable during the operation to provide back pressure.
The spring-loaded stop which is axially displaceable during operation, in cooperation with the auger, results in impulse feeding of a hydrolysate mass through the working space.
Changes in moisture content of the peat, its grading and the like, result in impulse reciprocations of the spring-loaded stop and in changes in back pressure within the working zone, hence in impulses outlet of the hydrolysate mass.
As a result of pulsation, the residence time of a mixture of peat and acid being treated in the working zone varies thus resulting in non-uniform destruction of polysaccharides, that is certain molecular chains are destroyed and others are not so that the hydrolysate mass thus obtained has a lower content of reducing substances, namely monosugars, the starting material is not completely utilized as regards sugars present therein, hence the apparatus has a low yield of finished product.
The use of two individual drives for destruction of polysaccharides in this apparatus results in high consumption of power.
In using the known apparatus on a large industrial scale, great quantities of starting material are processed due to the low yield of finished product, and a part of the starting material which does not undergo destruction is removed from further processing conducted for the production of fodder yeast.